The goal of the proposed research is to investigate the relationship of selected glutamate gene variants with cognitive and negative symptom response to the antipsychotic risperidone in first episode patients with schizophrenia who have little or no prior antipsychotic treatment history. Schizophrenia is a highly prevalent (-1% of population) and costly disease associated with marked and persistent cognitive dysfunction. Psychotic symptoms like hallucinations and delusions that occur with this disease often respond well to antipsychotic agents like risperidone. However, cognitive and negative symptom improvement after treatment is modest and highly variable from person to person. Variable responses to treatment are likely in part related to inter-individual genetic differences in drug response and neurotransmitter activity that affect a patient's likelihood of benefiting from a given medication. Characterizing these sources of variability and investigating ways to optimize treatments for individual patients will improve long term outcomes. This will be a pharmacogenetic study of 100 first episode schizophrenia subjects who have been treated with risperidone monotherapy for 4-6 weeks. Selected variants within two glutamate genes will be assessed for their relationships to change in cognitive biomarkers, neuropsychological performance, and clinical symptoms over the course of treatment. Changes in performance will be compared across selected genotype groups while controlling for population stratification assessed with genome wide markers. This research will be conducted in conjunction with a training program in cognitive neuroscience and genetics to prepare the PI for future pharmacogenetic studies using intermediate cognitive phenotypes and clinical symptoms to investigate sources of response variability and novel mechanisms of drug action.